<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        function shazi() {
            var a = document.getElementById("aaa").value;
            var b = document.getElementById("bbb").value;
            var c = document.getElementById("ccc").value;
            a = parseInt(a);
            b = parseInt(b);
            c = parseInt(c);
            if (a + b > c && a + c > b && b + c > a) {
                if (a == b || a == c || b == c) {
                    if (a == b && b == c) document.write('等边三角形');
                    else document.write('等腰三角形');
                } else {
                    document.write('是三角形');
                }

            }
            else document.write('不是三角形');
        }
    </script>
    <input type="text" id="aaa" placeholder="一条边">
    <input type="text" id="bbb" placeholder="两条便">
    <input type="text" id="ccc" placeholder="三条便">
    <button onclick="shazi()">确定</button>
</body>

</html>